Various types of wireless communication systems have become prevalent around the world. For example, cellular communication systems cover most major metropolitan areas as well as major highways through remote areas. Cellular systems permit individuals with cellular handsets to communicate with base stations that are connected to the public switched telephone network (PSTN) or some other communication network.
As with any communication system, cellular systems can leave coverage “holes” where the signal from the base stations cannot reach. The holes can be in tunnels, valleys, city streets between tall buildings, or any other location where a radio frequency (RF) signal is blocked.
Placing additional base stations where these coverage holes are located is not always an option. Base stations tend to be very expensive due not only to the cost of the equipment but also because of land acquisition costs. Additionally, large base station antennas may not fit within an area either physically or aesthetically.
One solution to hole coverage is to use smaller distributed antennas where coverage is needed but a base station is not warranted or desired. There are problems, however, with using a distributed antenna system.
Any system has a certain dynamic range over which signals are processed. For a system that has only one antenna port, the entire dynamic range is available to the single port signal. When the system has multiple antenna ports, as in the distributed antenna system, the same dynamic range is shared amongst the aggregate signal from all the ports. This reduces the dynamic range available for each port when multiple ports are simultaneously active. One problem with distributed antennas on a single signal path is that the aggregate signal along the signal path may exceed the system's allowable dynamic range. There is a resulting need in the art for a distributed antenna system with gain control.